Acoustically isolated ultrasonic transducer housing and flow meter

ABSTRACT

An ultrasonic transducer apparatus is provided. In one embodiment, the apparatus includes an outer housing, an inner housing disposed within the outer housing, and an ultrasonic transducer disposed within the inner housing. The outer housing has an aperture that enables pressurized fluid to enter the outer housing while allowing the outer housing to acoustically isolate the inner housing and the ultrasonic transducer from an additional component when the outer housing is connected to the additional component. Additional systems, devices, and methods are also disclosed.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the presently describedembodiments. This discussion is believed to be helpful in providing thereader with background information to facilitate a better understandingof the various aspects of the present embodiments. Accordingly, itshould be understood that these statements are to be read in this light,and not as admissions of prior art.

In order to meet consumer and industrial demand for natural resources,companies often invest significant amounts of time and money in findingand extracting oil, natural gas, and other subterranean resources fromthe earth. Particularly, once a desired subterranean resource such asoil or natural gas is discovered, drilling and production systems areoften employed to access and extract the resource. These systems may belocated onshore or offshore depending on the location of a desiredresource. Further, such systems generally include a wellhead assemblymounted on a well through which the resource is accessed or extracted.These wellhead assemblies may include a wide variety of components, suchas various casings, valves, hangers, pumps, fluid conduits, and thelike, that facilitate drilling or production operations.

Flow meters can be used to measure fluids (e.g., production fluids andinjection fluids) passing through conduits at a wellsite. In someinstances, operators use ultrasonic flow meters for such measurements.Ultrasonic flow meters include ultrasonic transducers for transmittingand detecting ultrasonic waves in a fluid passed through the meter. Theflowing fluid interacts with the ultrasonic waves transmitted throughthe fluid. This allows the received ultrasonic waves to be used to infercharacteristics of the fluid, such as velocity and volumetric flow rate.

SUMMARY

Certain aspects of some embodiments disclosed herein are set forthbelow. It should be understood that these aspects are presented merelyto provide the reader with a brief summary of certain forms theinvention might take and that these aspects are not intended to limitthe scope of the invention. Indeed, the invention may encompass avariety of aspects that may not be set forth below.

Embodiments of the present disclosure generally relate to ultrasonicflow meters and transducer assemblies. As noted above, ultrasonic flowmeters use transducers to measure characteristics of fluids fromultrasonic waves transmitted through the fluids. But while thesetransducers receive the ultrasonic waves transmitted through the fluids,they may also receive ultrasonic noise that can negatively impactmeasurement accuracy. One example of such noise includes ultrasonicwaves transmitted to the transducers through the body of the flow metersthemselves, rather than through the fluids. In certain embodiments ofthe present technique, however, ultrasonic transducers are acousticallyisolated from the flow meter bodies to reduce acoustic noise transmittedthrough the bodies to the transducers. In one embodiment, an ultrasonictransducer is provided in a housing, which is itself positioned inside asheath. Once installed, the sheath holds the housing in place within aflow meter body while acoustically isolating the housing from the flowmeter body. The sheath may also allow the housing to be in pressurebalance with the pressure of the measured fluid within the flow meterbody.

Various refinements of the features noted above may exist in relation tovarious aspects of the present embodiments. Further features may also beincorporated in these various aspects as well. These refinements andadditional features may exist individually or in any combination. Forinstance, various features discussed below in relation to one or more ofthe illustrated embodiments may be incorporated into any of theabove-described aspects of the present disclosure alone or in anycombination. Again, the brief summary presented above is intended onlyto familiarize the reader with certain aspects and contexts of someembodiments without limitation to the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of certain embodimentswill become better understood when the following detailed description isread with reference to the accompanying drawings in which likecharacters represent like parts throughout the drawings, wherein:

FIG. 1 generally depicts various components that can be installed at awell, including a gas lift injection system for facilitating production,in accordance with one embodiment of the present disclosure;

FIG. 2 is a perspective view of an ultrasonic transducer assembly thatcan be used in measuring flow of a fluid through a conduit, such asthrough a body of a flow meter of the gas lift injection system of FIG.1, in accordance with one embodiment;

FIG. 3 is an exploded view of the ultrasonic transducer assembly of FIG.2 in accordance with one embodiment;

FIG. 4 depicts a pair of the ultrasonic transducer assemblies of FIGS. 2and 3 coupled to a flow meter body with bushings in accordance with oneembodiment;

FIG. 5 is a detail view of one of the ultrasonic transducer assembliesinstalled in the flow meter body of FIG. 4;

FIG. 6 depicts a pair of the ultrasonic transducer assemblies of FIGS. 2and 3 coupled to a flow meter body in accordance with anotherembodiment; and

FIG. 7 is a detail view of one of the ultrasonic transducer assembliesinstalled in the flow meter body of FIG. 6.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Specific embodiments of the present disclosure are described below. Inan effort to provide a concise description of these embodiments, allfeatures of an actual implementation may not be described in thespecification. It should be appreciated that in the development of anysuch actual implementation, as in any engineering or design project,numerous implementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments, the articles “a,”“an,” “the,” and “said” are intended to mean that there are one or moreof the elements. The terms “comprising,” “including,” and “having” areintended to be inclusive and mean that there may be additional elementsother than the listed elements. Moreover, any use of “top,” “bottom,”“above,” “below,” other directional terms, and variations of these termsis made for convenience, but does not require any particular orientationof the components.

Turning now to the present figures, a system 10 is illustrated in FIG. 1in accordance with one embodiment. Notably, the system 10 is aproduction system that facilitates extraction of a resource, such asoil, from a reservoir 12 through a well 14. Wellhead equipment 16 isinstalled on the well 14. As depicted, the wellhead equipment 16includes at least one tubing head 18 and casing head 20, as well aswellhead hangers 22. But the components of the wellhead equipment 16 candiffer between applications, and could include a variety of casingheads, tubing heads, spools, hangers, sealing assemblies, stuffingboxes, pumping tees, and pressure gauges, to name only a fewpossibilities.

The wellhead hangers 22 can be positioned within hollow wellhead bodies(e.g., within the tubing and casing heads). Each of the hangers 22 canbe connected to a tubular string, such as a tubing string 26 or a casingstring 28, to suspend the string within the well 14. As will beappreciated, wells are often lined with casing that generally serves tostabilize the wells and to isolate fluids within the wellbores fromcertain formations penetrated by the wells (e.g., to preventcontamination of freshwater reservoirs). Tubing strings facilitate flowof fluids through the wells.

In some instances, resources accessed via wells are able to flow to thesurface by themselves. This is typically the case with gas wells, as theaccessed gas has a lower density than air. This can also be the case foroil wells if the pressure of the oil is sufficiently high to overcomegravity. But often the oil does not have sufficient pressure to flow tothe surface and it must be lifted to the surface through one of variousmethods known as artificial lift. Artificial lift can also be used toraise other resources through wells to the surface, or for removingwater or other liquids from gas wells. In one form of artificial lift,compressed gas is injected into oil wells. This injected lift gasdissolves in the oil (or other produced liquid) and also forms bubbles,lowering the fluid density and causing the oil to flow up wellbores tothe surface. The injected lift gas can then be collected from the oiland recycled.

As depicted in FIG. 1, artificial lift is provided by a gas liftinjection system 32, though it is noted that other arrangements forproviding artificial lift could be used. The injection system 32includes a source 34 of gas that can be injected into the well 14through the wellhead equipment 16. The gas can be compressed naturalgas, for example, which could be produced from the well 14 itself orfrom some other well. The source 34 can include a local or remotecompression facility, storage bottles, or any other suitable source. Thelift gas can be injected into the well 14 from the source 34continuously or intermittently.

A valve 36 (e.g., an adjustable choke or other control valve) regulatesflow of the gas from the source 34 into the well 14, while a flow meter38 measures the amount of gas flowing into the well. Any suitable flowmeter could be used, but in at least some embodiments the flow meter 38is provided as an ultrasonic flow meter having at least one ultrasonicgas transducer 40, which enables measurement of the gas flow ratethrough the flow meter 38 using ultrasound.

Gas lift valves 42 can be spaced along the tubing sting 26. These gaslift valves 42 open to allow lift gas injected down the well to flowinto the tubing string 26, where it dissolves in the fluid to beproduced (e.g., oil) and also forms bubbles. And as noted above, thispromotes flow of the fluid up the tubing string 26 to the surface.

The gas lift injection system 32 can also include a controller 44. Thecontroller 44 can be used to manage operation of the valve 36 (e.g.,regulating flow) and to determine flow rates of the injected fluidthrough the flow meter 38 with data from the transducer 40. Thecontroller 44 can include any suitable hardware or software forproviding this functionality. For instance, in one embodiment thecontroller 44 includes a processor for executing software instructions(e.g., stored in a suitable memory device) to control operation of thevalve 36 and to calculate flow rates through the flow meter 38 usingdata from the transducer 40. The controller 44 can also include variousinput and output devices to receive data or facilitate interaction withan operator. The flow rate through the flow meter 38 can be determinedin any suitable manner. In some embodiments, one or more pairs oftransducers 40 are used to measure transit times of ultrasonic waves influid flowing through the flow meter 38. Ultrasonic waves traveling inthe direction of fluid flow (from an upstream transducer 40 to adownstream transducer 40) will have a lower transit time than ultrasonicwaves traveling against the fluid flow (from the downstream transducer40 to the upstream transducer 40). The difference in these downstreamand upstream transit times can be used to determine the velocity andvolumetric flow rate of the fluid flowing through the flow meter 38.

One example of an ultrasonic transducer assembly 50 that can be usedduring measurement of velocity and flow rate through the flow meter 38is depicted in FIG. 2. In this embodiment, the ultrasonic transducerassembly 50 includes a transducer housing 52 (also referred to as aninner housing) received within a sleeve or sheath 54 (also referred toas an outer housing). In at least some instances, the sheath 54 isformed in whole or in part from material exhibiting high attenuation ofacoustic waves at the operating frequency of an ultrasonic transducer(e.g., transducer 112 of FIG. 5) within the transducer housing 52 sothat the sheath 54 acoustically isolates the housing 52 (and theenclosed transducer) from other elements of the assembly 50 and the flowmeter 38. This reduces acoustic short-circuiting of the transducerhousing 52 to the main body of the flow meter 38, reducing samplingnoise and increasing signal-to-noise ratio of the data collected by thetransducer. In at least some embodiments, the transducer housing 52includes a metal body (e.g., made with titanium, a HASTELLOY® alloy, aberyllium copper alloy, or another alloy) and the sheath 54 includes anon-metal body, such as a plastic body (e.g., made withpolyetheretherketone (PEEK), ULTEM™, or VESPEL®). Moreover, the plasticbody of the sheath 54 could also be filled with or reinforced by glassor other materials to facilitate acoustic isolation of the transducerhousing 52 from other components outside the sheath 54.

The depicted sheath 54 is coupled to a carrier 56. The sheath 54acoustically isolates the transducer housing 52 and its internalcomponents from the carrier 56, as well as from a flow meter body whenthe transducer assembly 50 is installed as part of a flow meter. Morespecifically, in at least some embodiments (e.g., those depicted inFIGS. 4-7), the sheath 54 enables the transducer housing 52 to bepositioned in space at a specific location within the meter body suchthat the housing 52 is in pressure balance with the pressure of thefluid passing through the flow meter during operation (e.g., gasinjected into the well 14 from the gas source 34). The sheath 54includes apertures or ports 60 that enable fluid to flow inside thesheath 54 about the transducer housing 52. Further, the sheath 54 isinterposed in the acoustic path between the transducer housing 52 andthe carrier 56 and attenuates any acoustic waves to or from thetransducer housing along this path. In instances in which the housing 52and the carrier 56 are both metal, the interposed sheath 54 alsoprevents metal-to-metal contact of the carrier 56 with the housing 52.

The carrier 56 includes a seal assembly 62 to inhibit leakage when theultrasonic transducer assembly 50 is installed in a flow meter body. Theassembly 50 also includes a connector 66 and wires 68 that enablecommunication with the controller 44 or other components. The connector66 can include a feed-through glass-to-metal seal that allows wires 68to pass into the carrier 56 and to the transducer housing 52 whilepreventing fluid flow through the connector 66.

Additional features of the ultrasonic transducer assembly 50 are shownin the exploded view of FIG. 3. For instance, the transducer housing 52includes a hollow tube 72 for receiving an ultrasonic transducer and acap 74 for closing the end of the hollow tube. The cap 74 includes aseal groove 76 for receiving a seal (e.g., an o-ring). When the end ofthe cap 74 is inserted into the hollow tube 72, the seal engages theinner wall of the tube 72 and isolates the interior chamber of thehollow tube 72 (in which the ultrasonic transducer is disposed) frompressure in the environment outside the housing 52. For example, in oneembodiment the housing 52 can maintain atmospheric pressure within itsinterior while exposed to flow meter operating pressures (e.g., up to10,000 psi) at its exterior. A spring 78 can also be provided to resistmovement of components (e.g., an ultrasonic transducer and spacingelements) within the housing 52.

The transducer housing 52 can be inserted into the sheath 54, which canthen be coupled to the carrier 56 in any suitable manner. In thepresently depicted embodiment, the sheath 54 and the carrier 56 includemating threaded portions 82 and 84 that allow these components to bethreaded to one another. A spring 86 provides a positive biasing forceon the transducer housing 52 and resists movement of the transducerhousing 52 within the sheath 54.

By way of further example, a flow meter 92 having a pair of ultrasonictransducer assemblies 50 coupled to a meter body 94 is depicted in FIG.4. In this embodiment, the ultrasonic transducer assemblies 50 areinstalled in-line with one another in a conduit 96 along the flow axisof the meter body 94, although the assemblies 50 could be installedoff-axis to measure diagonally with respect to the flow axis. When anartificial lift gas or other fluid is routed through the conduit 96 viainlet and outlet ports 98, the ultrasonic transducers of the assemblies50 can be used to determine fluid velocity and flow rate. The fluidflowing in the conduit 96 is pressurized and the ports 60 allow thepressurized fluid to pass into the sheaths 54 and surround thetransducer housings 52 of the assemblies 50 so that the housings 52 arein pressure balance with the fluid. As noted above, the housings 52 canbe sealed to inhibit flow of the pressurized fluid into the housings 52and to maintain a pressure differential between the interior andexterior of the housings 52 during use. The sheaths 54 of the assemblies50 acoustically isolate the housings 52 and inhibit transmission ofultrasonic waves between the two assemblies 50 through the meter body94.

As shown here in FIG. 4, the ultrasonic transducer assemblies 50 areinstalled in bushings 104 coupled to the meter body 94. Morespecifically, and as shown in greater detail in FIG. 5, the carrier 56of each assembly 50 is retained within a bushing 104 with a nut 106coupled to the bushing 104 via a threaded interface 108. That is, asshown here, the nut 106 has external threads that mate with internalthreads of the bushing 104. The nut 106 retains a lip of the carrier 56between the nut 106 and an internal shoulder of the bushing 104 andlimits movement of the assembly 50 within the meter body 94. As alsodepicted in FIGS. 4 and 5, the bushing 104 can be coupled to the meterbody 94 via a threaded interface 110. The bushing 104 can be made of anysuitable material, but in at least one embodiment the bushing 104 isformed of a non-metal material (e.g., plastic) and serves toacoustically isolate the carrier 56 from the meter body 94 and reduceacoustic short-circuiting between these two components.

An ultrasonic transducer 112 disposed within the ultrasonic housing 52is also shown in FIG. 5 in accordance with one embodiment. In at leastsome embodiments, the ultrasonic transducer 112 is capable of bothtransmitting and receiving ultrasonic waves. As will be appreciated,ultrasonic transducers 112 can include active elements for convertingelectrical energy to ultrasonic energy (for emitting ultrasonic waves)and vice versa (for measuring received ultrasonic waves). Any suitableactive elements could be used, such as piezoelectric ceramic, polymer,or composite elements. Further, the ultrasonic transducers 112 canoperate at any desired frequency. In at least some embodiments, theultrasonic transducers 112 operate at a frequency within a range of 80kHz to 400 kHz, inclusive, though other operating frequencies could beused in additional embodiments.

Electrical signals can be transmitted to and from the active elementsvia electrical leads 116. For instance, the leads 116 can communicateelectrical excitation signals to the transducer 112 to causetransmission of ultrasonic waves; the leads 116 can also communicateelectrical signals representative of ultrasonic waves received by thetransducer 112. In the depicted embodiment, a glass feed-throughconnector 118 seals the end of the housing 52 to prevent pressuretransmission while allowing the leads 116 to be connected to the wires68, thus facilitating electrical communication between the transducer112 and the controller 44 or other external components.

The active elements of the transducers 112 can be disposed in thetransducer housing 52 with various arrangements. As generally shown inFIG. 5, the transducers 112 can include tubes 124 for receiving internalcomponents (e.g., active elements). The ends of the each tube 124 can beclosed with a plate or window 126 and a cap or plug 128. In at leastsome embodiments the window 126 is welded to the tube 124.

While the ultrasonic transducer assemblies 50 can be coupled to themeter body 94 with bushings 104, they can also be coupled to meterbodies in different manners. For example, in one embodiment depicted inFIGS. 6 and 7, a flow meter 132 includes ultrasonic assemblies 50coupled directly to a meter body 134 without intermediate bushings. Themeter body 134 includes a conduit 136 with inlet and outlet ports 138.Like in the flow meter 92, the ultrasonic transducer assemblies 50 canbe positioned in the conduit 136 in-line with one another along the flowaxis of the meter body 134. Nuts 142 (which are identical to the nuts106 in at least some embodiments) can be threaded into the meter body134 at threaded interfaces 144 to retain the ultrasonic transducerassemblies 50. The sheaths 54 reduce acoustic short-circuiting betweenthe transducer housings 52 and the meter body 134 (through the carriers56) and attenuate ultrasonic noise that would otherwise be transmittedto the ultrasonic transducers 112. Experimentation has shown that theacoustic isolation described herein can improve the signal-to-noiseratio up to 28 dB compared to conventional methods, providing increasedmeasurement accuracy and reliability.

Additionally, although certain embodiments are described above withrespect to ultrasonic metering of an artificial lift gas injected in awell, it is noted that the techniques described above could be used inother contexts as well. For instance, the ultrasonic transducerassemblies 50 could be used in some embodiments to measure the flow ofother gases. Further, ultrasonic transducers can be acousticallyisolated, such as in the manners described above, and used forultrasonic metering of liquids in accordance with the presenttechniques. And while the acoustically isolated transducer assemblies 50can be used in oilfield contexts, such as those described above, suchassemblies could also be used for other applications.

While the aspects of the present disclosure may be susceptible tovarious modifications and alternative forms, specific embodiments havebeen shown by way of example in the drawings and have been described indetail herein. But it should be understood that the invention is notintended to be limited to the particular forms disclosed. Rather, theinvention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by thefollowing appended claims.

The invention claimed is:
 1. An ultrasonic transducer apparatuscomprising: an outer housing; an inner housing disposed within the outerhousing; and an ultrasonic transducer disposed within the inner housing;wherein the outer housing includes an aperture that enables pressurizedfluid to enter the outer housing while allowing the outer housing toacoustically isolate the inner housing and the ultrasonic transducerfrom an additional component when the outer housing is connected to theadditional component.
 2. The ultrasonic transducer apparatus of claim 1,wherein the additional component is a plug coupled to a flow meter body.3. The ultrasonic transducer apparatus of claim 2, wherein the outerhousing is threaded to the plug.
 4. The ultrasonic transducer apparatusof claim 3, wherein the inner housing and the plug are metal and theouter housing prevents metal-to-metal contact of the inner housing withthe plug.
 5. A method comprising: inserting an ultrasonic transducerhousing into a sleeve having a fluid port; coupling the sleeve to acarrier; and coupling the carrier to a flow meter body such that theultrasonic transducer is positioned in space within a conduit of theflow meter body and the fluid port places an interior of the sleeveabout the ultrasonic transducer housing in fluid communication with theconduit.
 6. The method of claim 5, wherein coupling the carrier to theflow meter body includes installing the carrier in a bushing andcoupling the bushing to the flow meter body.
 7. The method of claim 5,wherein coupling the carrier to the flow meter body includes couplingthe carrier to the flow meter body such that the ultrasonic transduceris positioned in-line with a direction in which a fluid would flowthrough the conduit when traveling between inlet and outlet ports of theflow meter body.
 8. The method of claim 7, comprising using theultrasonic transducer to measure flow rate of the fluid routed throughthe conduit.